Method and apparatus for shaping optical objects and the like



Feb; 26, 1946. v. WALKER v 2,395,700

METHOD AND APPARATUS FOR SHAPING OPTICAL OBJECTS AND THE LIKE FiledMarch 23, 1943 2 Sheets Sheet 1 INVENTOR 7/5705 Mimi/2 w I B m Feb. 26,1946. "v. WALKER 2,395,700

METHOD AND 'LPPARATUS FOR SHAPING OPTICAL OBJECTS AND THE LIKE FiledMarch 23, 1943 2 Sheets-Sheet 2 INVENTOR V/(fflfi W41 15/? y Y ATT NEYSPatented Feb. 26, 1946 UNITED STATES PATENT OFFICE.

METHOD AND APPARATUS FOR. SHAPING OPTICAL OBJECTS AND THE LIKE VictorWalker, Fort Erie,

Ontario, Canada, as-

signor to AlnCln, Inc., Buflalo, N. Y. I Application March 23, 1943,Serial No. $0,172 7 Claims. (01. 51-216) tween the work block and thegrinding or polishing tool. In accord with such prior practices the workblanks are customarily fastened upon the spindle block to be firmlysupported relative to the lap or other tool, as by means of some rigidmount device. A customary arrangement is to mount lens blanks uponspindles by means of a cementing substance such as pitch; and severalcementing substances are known which will satisfactorily maintain thework blanks relatively fixed to the spindle blocks while being routedthrough a series of successively finer grinding and polishingoperations. However, as a practical matter, the use of such rigidmounting systems precludes removal of the work blanks from the spindleblocks at stages intermediate of the complete grinding and polishingthereof. either because of the time and expense necessarily involved inbreaking the work pieces away from a set up and subsequently recementingthem into another set up or because of the difiiculty' met in trying toremount partially ground blanks upon rigid mount devices so as to bepresented to the subsequent grinding operation at the same anglerelative to the plane of relative movement between the spindle blockand-the too]. Also, the use of such pitch or other cementing substancesfor sticking work blanks upon the spindle block requires the applicationof special cleaning processes to the work removed from the blocks. Suchcleaning processes customarily involve washing the work pieces in somechemical solution adapted to dissolve remnants of the pitch or othercementing substance which invariably adhere to the work pieces upontheir removal from a cemented set up. The necessity for such cleaningoperations constitutes a further economic disadvantage, especially inconnection with large scale manufacturing operations where evenrelatively small additional expenses per unit add up to large sums, bothfrom the standpoint of additional pieces when they are cost and from thestandpoint of additional time required to complete the manufacture.

As a consequence of the considerations referred to herelnabove it iscustomary in the optical manufacturing arts to. plan the progress of themanufacturing operation so as to avoid removal of the work pieces fromtheir original stick up until completion of the block carried processesof the operation; and this type of work planing often necessarilyinvolves a routine which cannot obtain optimum efficiencies andeconomies. However, it is often most necessary or desirable to processthe work pieces under methods involving alternately setting up the workpieces on blocks and then unsetting them, and subsequently resettingthem. For example, as explained in my earlier patent application SerialNo. 442,198, it is particularly efficacious in connection with themanufacture of highest quality glass lenses her of alternate steps,

specifically, it is an objectof the or the like to alternately grind thelens blank and then to treat the ground surfaces with a stock piecereactive chemical solution to remove therefrom the debris of the priorgrinding operations, and then to further reduce the lens with a finerabrasive to obtain either a fine ground or polished surface, as the casemay require. In some instances, such grinding and chemical treating andregrinding and/or polishing processes may be carried on as a substantialnumand would require a corresponding number of set ups and .break oifs"of the work pieces relative to the spindle blocks. Obviously, eachresetting operation would require the application of great skill inorder to obtain resetting of the work pieces at the same angle relativeto the plane of relative movement between the spindle block and the toolso as to avoid unequal reductions of the stock pieces at differentportions thereof, and in fact this is almost an impossibility. In anyevent the expense and loss of time incidental to such resettingprocesses wouldin most cases be prohibitive.

It is an object of the present invention to provide an improvedmethodfor setting up work pieces of the character referred to and forpresenting them to'the grinding or polishing tools, as the case may beand to provide improved apparatus for use in conjunction therewith. Morepresent invention to provide an improved method of presenting a workpiece to the relatively moving tool, whereby the work piece will beadapted to antomatically adjust itself to the plane of relative movementtherebetween for optimum coordination between successive grindingerations in connection with different set ups of or polishing opgrindingor polishing actions of relatively moving 1:

tools. More specifically, another object of the invention is to providean apparatus of the character described whereby large numbers of likework pieces may be readily processed in connection with a series ofprocessing steps in improved manner. Another object of the invention isto provide an improved apparatus for the purpose described wherebysuccessive work pieces will automatically center themselves upon thework support device, and will be presented thereby to the go grinding orpolishing tool in such manner as to be free floating or self-adjustinginto accurate conformity with the disposition and operation of the toolso as to procure accurately coordinated successive grinding or polishingoperations upon the work pieces. Another object of the invention is toprovide the features and advantages referred to .hereinabove inapparatus of structurally simple and rugged form, and without use I ofadjustment mechanisms or the like such as would unduly complicate theapparatus. Other objects and advantages of the invention will appearfrom the specification hereinafter.

In the drawings:

Fig. l is a disassembled view, in section, of a 5 lens blank and holdingchuck of the invention;

Fig. 2 is a view corresponding to Fig. 1 of the lens blank mounted uponthe chuck and a grinding or polishing lap in conjunction therewith;

Fig. 3 is an elevation of a chuck and lap device of the invention forprocessing concave lens surfaces;

Fig. 4 is a plan of a multiple set -up chuck of the invention;

Fig. 5 is an elevation of the chuck of Fi 4;

Fig. 6 is a section through a multiple set-up chuck of the invention,showing in one instance the chuck and a lens blank in disassembledrelation, and in another instance the chuck and a lens blank inassembled condition; and a Figs. (and 8 are views similar to Fig. 6 ofother forms of the chuck of the invention.

The invention is illustrated in the drawings as being applied toapparatuses for use in the manufacture of glass lenses or the like, butit is to beunderstood that the invention is not so limited and that theprinciples thereof are equally adaptable to the manufacture of otherobjects having either similar or dissimilar shapes. For

example, whereas the drawings illustrate appa- 0 ratuses employing workand tool carrying spindles arranged to relatively rotate and oscillateso as to producespherical surfaces on the work pieces it will beunderstood that the work pieces and tools may be arranged to moverelatively with only straight line displacements to produce fiatsurfaces on the work pieces; and that any other desired type of relativemovement may be arranged for to produce any'shape desired.

The invention contemplates temporarily mounting a work piece such as aglass lens blank as illustrated in Figs. 1-2 at In; upon a holdingdevice having novel characteristics, such as the chuck or block devicewhich is designated genadapted to receive one end of a spindle l5; andit will be understood that the spindle I! may be mounted upon anysuitable type of rotating and oscillating support, as is well known inthe optical trades for example in connection with work and tool carryingspindle arrangements for processing spherical surfaces. A body portionl8 extends from the hub ll of the spindle concentrically thereof and isformed. with an axially extending flange I8 concentrically of the axisof rotation of the holder. A resilient support member 20 of circularplan form is fixed at its center, as by means or a fastener 22, to thebody portion of the holder so as to be carried thereby within itsflanged portion. The support member 20 is preferably formed of somerelatively soft and resilient material such as rubber or the like, andis shaped to normally have a set such as illustrated in Fig. '1, wherebythe support member assumes a dish shape such that the work contactingsurface thereof tends to contact the work piece only at the perimeter ofthe support member-and recedes therefrom toward the center of thesupport member. Hence, the surface of the work support member may beslightly wetted and the work blank then pressed firmly 'thereagainst, soas to deformthe support member to complement the contiguous surface ofthe work blank. Such pressing operation excludes the atmosphere frombetween the work blank and the support member, whereby an efiectgenerally known as a vacuum or suction is established between thesupport 20 and the lens blank.

Thus, as illustrated by Fig. 2, the lens blank is now fixed upon thechuck l2 with the optical axis of the lens blank coincident with theaxis of rotation of the chuck. As shown by the drawings, the chuck bodyand the work support members are so dimensioned and arranged thatsubsequent to mounting of the work piece upon the support 20 the workpiece is supported to be partially embraced at the peripheral edgethereof by the flange structure it of the chuck. Hence, the lens blankis automatically centered upon the chuck while being supported therebyto be free to float relative to the chuck within a narrow range ofpossible movement relative to the chuck, whereby whenever a grinding orpolishing lap as at 25 (Fig. 2) is pressed against the work piece in.opposition to the forces of the spindle IS the work piece willautomatically adjust itself into perfectly matching conformity with the.

grinding and polishing practice. Thus, as abrasive material is fed tothe lap 25 the exposed surface of the work piece will be reduced by theaction of the lap to produce the spherical surface form prescribed forthe work piece. Due to the novel mounting of the work piece upon theholder H the work piece is minutely fioatable and self-adjusting to thelap 25, whereby the bearing between the work blank and the lap will beautomatically equalized over all areas of the work piece, and wherebyunequal or otherwise inaccurate reduction of the work piece will beavoided.

As illustrated by Fig. 2, when the work blank is erally at II. Theholder l2 comprises a hub M fixed upon the chuck the support member 20is tiguously placed surface of the stock piece.

thereby elastically deformed, whereby the support member thereuponresists to a substantial degree any tendencies toward further elasticdeformation thereof. However, in event the resiliency of the supportmember is further overcome by forces from externally thereof, thesupport member will thereupon be forced against the body portion I6 I'piece relative to the tool, and subsequently more firm support thereofagainst movements relative to the holder.

A notch is cut into a side wall portion of the flange structure of theholder, as indicated at 28; and the notch 28 is soproportioned andarranged as to enable the operator to thrust a blank whereupon the workblank is freed of its connection with the holder. Sludge escape openlugsare preferably provided as indicated at 29 to enable the mud-or sludgeof grinding or polishing operations to escape from behind the supportcup 20, so as to avoid possible interference thereby with propersupporting action of the member 20.

Fig. 3 illustrates a holder or chuck 30 of the invention for use inprocessing a concave surfaced work piece 3|; and it will be understoodthat the chuck of Fig. 3 may be generally similar to the chuck of Figs.1-2 in that the elastic work piece support device thereof will have itsouter surface curved to a degree that is somewhat sharper than thedegree of curvature of the con- A convexly surfaced lap 32 is shown foruse in conjunction with the holder 30.

Figs. 4 and 5 illustrate generally the external form that a holder ofthe invention for multiple lens blank set ups may assume. The holder isillustrated as being generally in the form of a sphericallyrsuriacedblock 33 terminating in a hub portion 34 for connection to a spindle(not shown). The outer face 35 of the block 30 is shaped to a curvehaving a radius slightly less than the radius'of the curve to which thework pieces 36 are to be shaped; and the work blank mounting portions ofthe block 33 are arranged to support the work pieces in such manner asto. protrude from the block (Fig. 5) to complement the curvature of thelap to be brought into action against the work pieces. Finger nailnotches as indicated at 31 are formed in the block 33 to facilitateupsetting of the vacuum connections between the work pieces and therespective holder cups.

Fig. 6 illustrates, by way of example, one method for mounting lensblanks upon a block generally similar to the block ofFigs. 4-5. In Fig.6 the block is illustrated as comprising a body portions throughout theblock surface to generally accommodate the body portions ofcorresponding lens blanks and blank supporting cups 48-48. As in thecase of Figs. 1-3, the supporting cups 48 are of elastically deformablematerial such as rubber or the like, and are cupped at their outersurface portions so as to cooperate with the back surfaces of the lensblanks to provide the' suction mounting effect referred to hereinabove.Each cup 48 carries a threaded stub 49 adapted to be inserted through acorresponding perforation in the block for threaded connection with awing nut 50 disposed therebehind.

Thus, it will be understood that in order to mount a plurality of lensblanks 52 upon the block 40 the blanks ar simply pressedagainstcorresponding mounting cups 48 so as to be concentric thereof. Thesuction-united blank andcup unit is then inserted into a correspondingrecessed portion 48 of the block so that the stub 49 thereof extendsthrough the block. The corresponding'wing-nut 50 is then screwed uponthe stub to draw the cup down into seated position relative to theblock. The block and cup elements are so dimensioned and relativelyarranged that when the wing nuts 50 are tightened upon the stubs 49 thecorresponding cups 48 are pulled upon to seat the overhanging annularedge portions of the lens blanks firmly against comple-' mentarilyshaped annular shoulder portions 54 of the block 40. An annular washer55 of soft and resilient material such as' rubber or the like ispreferably disposed upon each shoulder 54 of the block to provide aresilient support for the corresponding lens blank when pulled intoseated relation upon the block. Hence, it will be understood that eachlens blank will be thereby mounted upon the block so as to be slightlytiltable relative to the block, and is minutely floating and 40self-adjustable into accurately matching conby reason of the rigidity ofthe body of the block 40.

The block 40 and more specifically the recessed portions 46 thereof areso dimensioned and proportioned as to be adapted to support the lensblanks 52 in such manner that the marginal edges of the lens blanks arepartially enclosed by the side walls of the recessed portions 46 of theblock. Consequently, as the lens blank-cup units are pulled into thecorresponding recessed portions of the block the lens blanksautomatically center themselves within the recesses, and the blockthereupon becomes enabled to maintain the lens blanks against lateraldisplacement relative to the block inresponse to forces transmittedthrough the processing tool 58. At the same time the lens blank isthereby supported to be minutely self-adjusting to the lap 58 whilebeing basically supported by the body of the block 40 in positivemanner, whereby the improved work piece employed if desired, for thepurposes explained hereinabove.

Fig. '7 illustrates another form ofa multiple block device of theinvention wherein a block block is recessed, as at 45-45 at multipleposi- 75 60 which is generally similar to the block 40 of Fig. 6 isrecessed as at 62 to receive in cradled relation therein a plurality ofwork piece supporting cups 84. The cups are externally faced so as to beadapted to cooperate with the contizuous face portions of thecorresponding work pieces 65 to procure the vacuum type mountingconnections therebetween referred'to hereinabove. Each cup support it isprovided with a centrally extending stub 66 which may be permanentlyscrewthreaded or otherwise connected asoonoo provements in the art ofholding work pieces such as lens blanks or the like in bearing relationagainst grinding or polishing or other processing tools whereby the workblanks are adjustable to accurately match the attitude of the tools.Hence, processing of difierent portions of the work blanks to differentdegrees is avoided, and great into mounted relation upon the block 50.The

recessed portions of the block and the cups '64 are so dimensioned as toadapt the cups to receive the work blanks 65 in vacuum fixed relation,as explained hereinabove, and to thereby: support the work blanks to bepartially embraced at their sides by the side walls 'of the block re-'cesses to provide the self-centering or lateral guiding operationreferred to. The cups 54 will be preferably so shaped as to assume thecondition illustrated at the left of the spindle in Fig. '7

economies with respect to time and labor costs involved in connectionwith setting and u setting and resetting of the work blank are efiected.

It will also be understood that the method and apparatus of theinvention provides further important improvements and advantages notpreviously referred to. For example, whenever the invention is employedin conjunction with the grinding or polishing of work pieces through useof successively finer grades of abrasive, as in the when the work blankis mounted upon the cup,

whereby a slight gap will exist between the body of the block 60 and therear surface of the cup '54, as indicated at 68. Hence, the work blankwill be supported by the cup to be free to wobble to a slight degreerelative to the block 50 for accurate adjusting of the work blank to theatlens making arts, each block or chuck device of the invention may beretained in its designated abrasive department of the manufacturingoperation. For example, one chuck or block of the titude of the lap 10when pressed against the work blanks. However, as in the case of thepreviously describedforms of the invention, the cups 64 will besupported basically in a firm manner, whereby efficient surfacing of thework blanks may be eifected. Sludge escape openings are pro-- vided inthe block 80, as indicated at ll, and finger nail notches are providedas explained hereinv above in-connection with other forms of the holder.

Fig. 8 illustrates another form of the invention which is adapted foruse in connection with the processingvof sharp-edge lenses or the like;that is, lenses such as indicated at I2 wherein the optical faceportions thereof merge directly into one another without having straightedge wall portions therebetween as in the case of the lens blanksillustrated by the other figures of the drawings. Thus, the type of lensblank illustrated by Fig. 8 mustof necessity-be supported by the blockdevice of the invention in such manner that the knife-edge portion ofthe work blank is disposed externally of the block 13. This is requiredin order that the lap 14 may clear the surface I of the block 13 whilebeing effective against the work blanks 12. Consequently,'the work blanksupport member is formed, :as illustrated -at i5 invention may bedesignated to a "coarse" grinding department of the manufacturingoperation, and quantities of lens blanks or the like may be successivelymounted upon the holder and ground under a correspondinglap with the aidof an abrasive graded to the requirements of the department. Uponcompletion of such coarse grinding operations thework pieces may then beremoved from the holding device and cleaned of remnants of the coarsegrinding abrasives and then delivered to-a fine grinding department. Thework pieces will thereuponbe mounted successively upon another holdingdevice of the invention which has been designated to remain in operationin the fine grinding department. The corresponding grade of fineabrasive will then be employed in conjunction with a corresponding lapdevice, until the fine grinding is complete. Hence, it will beunderstood that in order to prevent contamination of successively finergrinding operations with remnants of coarse abrasives .from precedingoperations in connection with transfer of work pieces to successivelyfiner grindingdepartments will require only the careful washing of thework pieces themselves. Inasmuch as it is relatively easy to clean asmall lens blank or the like, while it is relatively diflicult to begenerally similar to the support cups 64 of Fig. 7 except that they areso dimensioned as to project the work blank edges beyond the contour ofthe block, as shown in Fig. 8. Again, the cups 15' are preferablyarranged to provide slight gaps between the cups and the block, asindicate'd at '16, to enable the cup and work blank units to wobbleslightly relative to the-block for self-adjusting purposes. Sludgeescape openings are provided as indicated at 11.- In view of the factthat the work blanks are supported '50 as to be permitted to wobblesomewhatrelative to the block 12, it is preferable to slightly round theto clean an entire block or chuck device of adhering abrasive granules,it will be understood that the invention provides further an importantsafeguard to the manufacturing operation.

Another important feature and advantage which is provided by theinvention resolves from the fact that the use of cementing pitch or thelike is avoided. Consequently the use of a pitch dissolving solvent islikewise avoided, and it becomes unnecessary to store quantities ofpitch and solvent substances at the factory, whereby the fire hazardfactor of the operation is greatly reduced. Another important featureand advantage of the invention in conjunction with the a multiple blockform thereof is provided in view of edges of the lap 14, as indicated atl8. Thus, f even though the work blanks might assume unintended tiltedattitudes relative to the block subsequent to uncovering movements ofthe lap I4, the work blanks will be easilycammed back by the noseportion 18 of the lap-into proper posi-' .tion and attitude uponsubsequent retumof the lap 14 to'work blank covering position.

Thus, it will be understood that the method and apparatuses of theinvention provide im- Hence, unnecessary to completion of thesatisfactory work pieces remaining on the block, is avoided.

It will be understood that although only a limited number of forms ofthe invention have been shown and described in detail, the-invention isnot so limited but that various changes may be made therein withoutdeparting from the spirit of the invention or the scope of the appendedclaims.

1. In combination, an abrading lap, a holder for carrying a lens blankto be pressed against said abrading lap, said holder comprising a rigidbody portion recessed to accommodate a lens blank in partially embeddedrelation therein to present one face portionof said lens blankexteriorly of said holder and to be laterally supported by the recessedportion of said body portion, a support member of elastic material fixedto said body portion interiorly of the recessed portion thereof andhaving a surface adapted to register connection therebetween, saidsupport member when mounted thereon to float relative to said holderbody portion for-minor adjustments of attitude relative thereto, saidholder body portion being apertured'to provide a channel for escap ofsludge from between said support member and said holder body portion.

4. In combination, an abrading lap, a holder for carrying a lens blankto be pressed against said abrading lap, said holder comprising a rigidbody Portion recessed to accommodate a lens blank to be inset therein soas to present one face of said lens blank exteriorly of said holder, 9.support member of rubber suction cup form fixed at its center to saidbody portion and having a cupped outer surface adapted to cooperate withthe lens blank to provide a suction type mounting connectiontherebetween, said support member being normally retracted at itsperimetral portion away fromsaid holder body portion and adapted to flexto permit the lens blank when mounted thereon to float relative to saidholder for mino adjustments of the lens blank attitude relative to saidlap when pressed therea'gainstgsaid holder being adapted to fiex topermit the lens blank 1 when mounted thereon to rock relative to said.

holder for minor adjustments of the lens blank attitude relative to saidlap when pressed thereagainst, said holder body portion being notched atone side of said recessed portion thereof to permit insertion of aprying tool therethroug'h for separating said lens blank and saidsupport member at one side of the suction'connection thereof.

body portion recessed to accommodate a lens blank in partially embeddedrelation therein to present one face portion of said lens blankexteriorly of said holder and to be laterally supported by the recessedportion ofsaid body portion, a support member of elastic material fixedto said body portion interiorly of the recessed portion thereof andhaving a surface adapted to register with an inner face portion of saidlens blank when disposed upon said holder, said support member surfacebeing shaped so as to cooperate with the lens blank to provide asuction" type mounting connection therebetween, said support memberbeing adapted to flex to permit the lens blank when mounted thereon torock relative to said holder for minor adjustments of the lens blankattitude relative to said lap when pressed thereagainst. said holderbody portion being apertured in communication with "the space behindsaid support member to provide a channel for escape of abrading sludgefrom between said support member and said holder body portion.

3. A holder for carrying a lens blank or the like to a grinding orpolishing operation, said holder comprising a rigid body portionrecessed to permit a lens blank to be inset therein so as to present oneface of said lens blank exteriorly of said holder, a support member ofelastic material fixed to said body portion and having a surface adaptedto register with the inner face of said lens blank when carried by saidholder, said support member surface being shaped so as to cooperate withthe lens blank to provide a suction type mounting connectiontherebetween, said support member being adapted to flex toward and awayfrom said holder body portion to freely permit the lens blank bodyportion being notched at one side of said recessed portion thereof topermit insertion of a prying tool therethrough for separating said lensblank and said support member at one side of the suctionconnection'thereof, said holder body portion being apertured incommunication with the space behind said support member to provide achannel for escape of abrading sludge from between said support memberand said holder body portion.

5. In combination, an abrading lap, a holder for carrying a plurality oflens blanks to be pressed against said abrading lap, said holdercomprising a rigid body portion recessed to accommodate said 1 lensblanks in partially embedded relation therein to present outer faceportions of said lens blanks exteriorly of said holder while beinglatthe lens blank attitude relative to said lap when pressedthereagainst, said holder body portion being notched at one side of eachof said recessed portions thereof to permit insertion of a prying tooltherethrough for separating said lens blanks and said support members atone side of the suction connections thereof.

6. In combination, an abrading lap, a holder for carrying a plurality oflens blanks to be pressed against said abrading lap, said holdercomprising a rigid body portion recessed to accommodate said lens blanksin partially embedded relation therein to present outer face portions ofsaid lens blanks exteriorly of said holder and to be laterally supportedby the recessed portions of said body portion, a support member ofelastic material fixed to said body portion interiorly of each of therecessed portions thereof and having a surface adapted to register withan inner face portion of a lens blank when disposed upon said holder,said support member surface being shaped so as to cooperate with thelens blank to provide a suction type mounting connection therebetween,

said support member being adapted to flex to permit the lens blank whenmounted thereon to rock relative to said holderior minor adjustments ofthe lens blank attitude relative to said lap when pressed thereagainst,said holder body portion being apertured in communication with each ofthe spaces behind said support members to provide channels for escape ofabrading sludge from between said support members and said holder bodyportion.

'7. A support device for holding a lens blank or the like against agrinding or polishing device whereby to permit surface-reducing or saidlens blank about a symmetry axis xtending normally to and centrally ofthe front surface of the blank, said support device comprising incombination, a base, an elastic cup member formed to peripherally abutthe rear surface of the blank while being substantially coextensive withthe marginal confines thereof and adapted to be pressed thereagainst invacuum-sealed connection manner while exerting an outward thrustthereagainst. and mounting means extending from only the central reaportion 01' said cup member for mounting connection of the latter uponsaid base. said base having a marginal ledge thereon encompassing theperimeter of said blank and normally in spaced relation therefrom formaintaining said blank against undue lateral displacement. whereby saidblank may be pressure-attached upon said cup member to .be connectedthereby to said base and held thereby in operative position against asurface-reducing operation while being free to rock universally aboutsaid central mounting connection to permit surface-reduction of saidblank symmetrically of said axis.

VICTOR WALKER.

